Unique selectivity reversal in Am³⁺–Eu³⁺ extraction in a tripodal TREN-based diglycolamide in ionic liquid: extraction, luminescence, complexation and structural studies

Abstract

An N-pivot diglycolamide extractant (DGA-TREN) was synthesized for the first time and its complexation behaviour was studied towards trivalent lanthanide/actinide ions. The solvent extraction studies suggested a unique selectivity reversal in the extraction of trivalent actinides versus trivalent lanthanides which was observed performing extraction studies in an ionic liquid vis-à-vis a molecular diluent for a tripodal TREN-based diglycolamide ligand (DGA-TREN) vs. a tripodal diglycolamide ligand (T-DGA) which may have great significance in radioactive waste remediation. The nature of the bonding to Eu(3+) ion was investigated by EXAFS as well as by DFT calculations.

Benzene-centered tripodal diglycolamides: synthesis, metal ion extraction, luminescence spectroscopy, and DFT studies

“…The group of Scott reported the extraction of actinide ions using millimolar concentrations of tripodal DGA ligands (in dichloromethane) where each DGA moiety was appended to a separate benzene ring (this ligand is termed as C3-DGA) and the extraction of Eu 3+ was quite efficient even at 1 M HNO3. 6 Recently, we have reported the extraction behaviour of a novel N-pivot tripodal DGA ligand (TREN-DGA) 7 with unique selectivity reversals as compared to the T-DGA, which makes the tripodal DGA ligands an interesting class for actinide ion separation from the HLW. Previously reported tripodal DGA ligands such as T-DGA and TREN-DGA appear to have higher flexibility as the DGA pendant arms are appended to a single atom.…”

Evaluation of two aza-crown ether-based multiple diglycolamide-containing ligands for complexation with the tetravalent actinide ions Np4+ and Pu4+: extraction and DFT studies

“…This suggests that the extraction of Np 4+ ensures that of Pu 4+ as well. Knowing very well about the poor extraction of UO 2 2+ ion with multiple DGA-containing ligands, 18,[21][22][23] decontamination of the actinides can be easily achieved from U. The following sections include results of the other extraction studies.…”

“…Other multiple DGA ligands, containing three DGA arms, have also been studied over the years, which include those with a central carbon or nitrogen atom or a set of benzene-centered tripodal DGA ligands. [20][21][22] Recently, we reported the rst time study on the extraction of actinides using a tripodal DGA ligand where the DGA arms are tethered to a triazamacrocycle scaffold (L I ; Fig. 1).…”

Highly Efficient Extraction of Trivalent f‐Cations Using Several N‐Pivot Tripodal Diglycolamide Ligands in an Ionic Liquid: The Role of Ligand Structure on Metal Ion Complexation

“…Multiple DGA ligands where the DGA arms are tethered to a central atom or a scaffold such as calixarene, pillar[5]arene, or benzene are reported to enhance the metal ion extraction enormously from acidic feeds. Recently, N pivot tripodal DGA ligand (termed as TREN‐DGA) was synthesized which showed very interesting extraction/separation behaviour of trivalent lanthanide and actinide ions It showed contrasting behaviour when compared with an analogous C ‐pivot tripodal DGA ligand (termed as T‐DGA) . While the extraction of Am(III) (quantified as the distribution ratio values) was about 30 times lower with TREN‐DGA as compared to T‐DGA, the extraction of Eu(III) was 85 times lower with TREN‐DGA as compared to T‐DGA.…”

“…As mentioned above, the use of TREN‐DGA indicated a unique reversal in the extraction behaviour of lanthanides and actinides in RTIL solvent vis‐a‐vis a molecular diluent . It was of interest, therefore, to investigate the extraction behaviour of trivalent actinide (Am 3+ ) and lanthanide (Eu 3+ ) with a series of N ‐pivot DGA ligands dissolved in an RTIL.…”